1. Field of the Invention
The present invention relates to a yarn piecing method in a yarn spinning machine provided with a yarn piecing means and in which a spun yarn spun by and delivered from a yarn forming means and another yarn withdrawn from a yarn package on which the spun yarn is wound are pieced to each other.
2. Description of the Related Art
Generally speaking, a yarn spinning machine such as a fasciated spun yarn spinning machine includes a drafting means, a yarn forming means, a yarn taking-up means, a yarn winding means, and the like. When staple fiber bundles are supplied, a spun yarn such as a fasciated spun yarn is spun in the yarn forming means and wound on a yarn package by the yarn winding means.
When a yarn breaks in the yarn producing process, a yarn piecing operation is usually carried out. Namely, the yarn piecing operation includes the steps of, first, stopping a yarn winding means once; sucking a spun yarn delivered from a yarn forming means (referred to as a first yarn hereafter) by a first yarn sucking means provided on a yarn piecing apparatus; withdrawing a yarn from a yarn package (referred to as a second yarn hereafter) by a second yarn sucking means; and piecing the first and second yarn to each other by carrying the two yarns to a yarn piecing means such as a yarn splicer or a yarn knotter.
In this conventional yarn piecing method, a yarn spun by and delivered from a yarn forming means during a yarn piecing operation is sucked and stored in a yarn storing means provided between a yarn taking up means and the yarn piecing means. Then, when the yarn piecing operation is completed, the non-rotated yarn package is restarted to rotate in such a way that the rotational speed thereof is rapidly increased with a predetermined acceleration to take out the yarn stored in the yarn storing means. Thereafter, the rotational speed of the yarn package is changed to a predetermined yarn winding speed to wind up a spun yarn delivered from the yarn forming means.
When the yarn piecing operation is completed, a condition of whether the spun yarn thus pieced to each other runs normally or not is detected by the yarn sensor.
When the yarn does not run normally, the sensor outputs an alarm signal to stop an operation of the drafting means and thereby to stop the spinning operation in the yarn forming means. Simultaneously, the yarn winding operation in the yarn winding means is stopped by the alarm signal and the yarn piecing means is moved to a spindle to which the yarn piecing operation is required.
In the yarn piecing method as explained above, in which the condition of whether the yarn piecing operation is successful or not is discriminated after the yarn piecing operation is finished, when a yarn is not delivered from the yarn forming means due to, for example, fibers being clogged in a nozzle provided in the yarn forming means, a problem arises of rollers and apron belts provided in the drafting means breaking because a staple fiber bundle supplied from the drafting means is not sucked into the yarn forming means for the 10 to 15 seconds of the yarn piecing operation, but is wound up on the drafting rollers provided in the drafting means.
On the other hand, once the yarn piecing operation is not successful, even if the failure of the yarn piecing operation is caused by the yarn piecing means, there is a possibility of the fibers clogging the nozzle in the yarn forming means.
Therefore, the following procedure is taken in this situation without repeating the yarn piecing operation; The operation mode of the yarn piecing operation is first changed to an operator call mode thereby an operator checks for defects of the yarn or malfunctions of the yarn forming means or yarn piecing means, then the operation mode is changed to a yarn piecing mode to restart the yarn piecing operation.
Accordingly, another problem arises in that the amount of operational work for the operator is increased.
Further, in a plied spun yarn spinning machine, in which two spun yarns spun from separate yarn forming means arranged adjacently and in parallel to each other are plied and wound simultaneously on a yarn package, as shown in Japanese Examined Patent Publication No. 63-42012, when a yarn piecing operation is needed, it is necessary that the two spun yarns each be picked up by a sucking means from the yarn forming means and the yarn package respectively and be carried to the yarn piecing means.
In this system, when only one spun yarn is picked up from any one of the yarn forming means and the yarn package by the yarn picking up means, one yarn picked up from any one of the yarn forming means and the yarn package is pieced with two yarns picked up from the rest or one yarn picked up from any one of the yarn forming means and the yarn package is pieced with one yarn picked up from the rest.
This causes a problem in that a yarn having abnormal knotted portions is wound on a yarn package.